Method and apparatus for operating steam generators



NOV. 24, 1936. B CAMPBELL 2,061,831

METHOD AND APPARATUS FOR OPERATING STEAM GENERATORS Filed NOV. 15, 1955 INVENTOR.

Patented Nov. 24, .1936

UNETED STATES FAYEN'E" @FQFEQE METHOD AND APPARATUS FQR OPERATING STEAM GENERATORS 3 Claims.

The method is applicable to the once-through or non-circulating type of generator and'consists of so regulating the flow of water to the enerator, that the steam delivered therefrom 5 Will be of approximately a uniform temperature, regardless of the load upon the generator. This method is particularly applicable to the generator construction shown in my application bearing Serial No. 13,703, filed March 29, 1935 and 1 entitled Steam generators.

The mechanism for carryingout the method consists of a novel arrangement of thermostatically actuated electric switches, which are responsive to temperature conditions in the generator and. steam line and which control the flow of current through an electro-magnet, which, in turn, actuates a valve, which controls the flow of water to the generator.

In operating the generator above referred to, (but when not using the steam temperature control shown) I have found that the temperature of the delivered steam varies with the amount of steam being delivered, if a fixed amount of Water is maintained in' the generator, and that the temperature is highest, when the amount of steam being delivered is greatest; and I have found that the temperature of the delivered steam varies inversely with the amount of water maintained in the generator.

My improved method of operating the oncethrough type of generator consists in maintaining a certain predetermined amount of water in the generator, when the temperature of the delivered steam is below a certain point and in maintaining a certain greater amount of water in the generator, when the temperature of the delivered steam is higher than the above mentioned point. By the use of this method, the delivered steam will be of approximately a uniform temperature and will be positively held between the minimum and maximum temperatures for which the apparatus is adjusted. The method of operation may be accomplished by the use of the mechanism described below.

Referring to the drawing, numeral 4 designates a once-through type of steam generator, 5 a tube for supplying fuel and air to the upper part thereof, 6 a tube through which the products of combustion may be discharged from said generator, 1 a tank for supplying water, 8 a water pump, 9, l0, and H pipes connecting the generator, pump and supply tank, l2 a valve adapted to control the flow of Water and direct it either to the generator through the pipe 9, or back to the supply tank through the pipe l3. This valve is actuated in one direction by the armature it of the electro-magnet l4 and in the opposite direction by the spring l5. Electrical current is carried by the conductors 20.

When the magnet is energized, the valve I2 is open and the water will flow from the pump back to the supply tank; and when the magnet is not energized, the valve 12 will be closed and water will be forced to the generator through the pipe 9. The check valve ll prevents water from discharging from the generator, when the valve I2 is open.

The thermal switches l, 2, and 3 are provided to control the flow of current through the coil of the electro-magnet Hi. These thermal switches may be of any well known type such as, for instance, a steel tube through which passes a brass rod, one end of which is fixed and the other end of which abuts against the movable member of a switch, said tube being in communication with the generator or the steam line, as the case may be, so that steam or water may enter said tube and effect the movement of the switch.

Thermal switch 8 is influenced by conditions within the generator at a certain point; thermal switch 2 is influenced by conditions within the generator at a certain point beyond the first point; thermal switch 3 is influenced by the temperature of the steam in the delivery pipe l8. A source of current, such as the battery I9 is provided.

When there is insufiicient water in the generator to influence thermal switch I, and the temperature of the delivered steam is below a certain predetermined point, the thermal switch i will be open, the thermal switch 2 will also be open and the thermal switch 3 will be closed. The magnet M will, therefore, not be energized and the valve l2 will direct the water from the pump to the generator. When there is a sufficient amount of water in the generator to influence switch i, said switch will be closed and current Will flow from the battery through switch I, the coil of the magnet M and the switch 3 to the ground, energizing the magnet and opening the Valve i2 and causing water to flow back to the supply tank. If the temperature of the steam in the delivery pipe rises above a predetermined point, thermal switch 3 will open, the circuit through the magnet will be broken, and water will be again pumped to the generator. When there is a sufficient amount of water in'the generator to influence thermal switch 2, a circuit will be closed from the battery through switch I, the

coil of the magnet i 4, and switch 2 to the ground.

The magnet will, therefore, be again energized, the valve [2 opened, and the water delivered back to the supply tank I. If now, the temperature of the steam in the delivery pipe l8 again falls below the above mentioned predetermined point, the switch 3 will close and the opening or closing of switch 2 will be ineffective and the flow of water will again be under the control of switch I.

I claim:-

1. The method of operating a series steam generator, which consists in maintaining a certain weight of water in said generator, when the temperature of the steam at a certain point in said generator is below a certain degree, and maintaining a definitely greater weight of water in said generator, when the temperature of the steam at the above mentioned point is higher than a certain degree, and limiting both the minimum and maximum weights of water which may be present in the generator, irrespective of the temperature of the steam at the above mentioned point.

2. In combination with a steam generator of the once-through type, a first thermal switch, which is responsive to the temperature within the generator at a certain point, a second thermal switch, which is responsive to the temperature within the generator at a certain point beyond the first point, a third thermal switch, which is responsive to the temperature of the steam being delivered from the generator, a valve controlling the flow of water to the generator, an electro-magnet controlling said water valve, a grounded source of electrical energy, a circuit from said source of energy to the first switch, thence to the electro magnet, thence to both the second and third switches in parallel, thence to the ground, and from the ground to the source of energy.

3. In combination with a series steam generator, a first thermal switch, which is responsive to the temperature within the generator at a certain point, a second thermal switch, which is responsive to the temperature within the generator at a point beyond the first point, a third thermal switch, which is responsive to the temperature in the generator at a point beyond the second point, electrically operated means for controlling the flow of water to the generator, a grounded source of electrical energy, a circuit from said source of energy to the first switch, thence to the water control means, thence to both the second and third switches in parallel, thence to the ground, and from the ground to the source of energy.

OSMON B. CAMPBELL. 

